AOA, What's it good for?: Best Step Climbs and other Phases of Flight

(new edit: please see bottom post for using the FPV along with numeric readout)
(past edit: please see comments in post near the bottom about targeting AOA numbers; but it still follows this first part, thanks!)

I just noticed that AOA can now be set at the bottom of the screen. New to the update, or I missed it before?

For step climbs this is what I (currently) believe is true:

You can optimally control your step climb using AOA as your reference instrument.

The ceiling of each of your steps is, subject to your throttle limits, where you’re just on the edge of not being able to hold AOA = AOAe. AOAe is the angle that gives you best aerodynamic efficiency for all phases of flight.

So how do you maneuverer AOA to target AOAe with your throttle set at the limits (for that phase of flight)? You slowly adjust pitch, which translates to adjusting speed, and that gives you the AOA control.

When you just start losing ability to hold AOA at AOAe, you’re at your current step ceiling. Burning more fuel is the only thing that will let you resume the climb while holding AOAe.

AOAe is a low single digit number of degrees unique to each aircraft type in clean configuration. You only need to learn that number once for each aircraft type. Maybe start with 4° (I need to give credit to A_Hippopotamus for that number, how do I do that here? - I’m a forum amateur).

I believe the step climb intends to be a good approximation of what is actually a smooth climb. You do it as a step due to air traffic congestion management. If you didn’t have that to worry about, you would (for the power setting limits) climb just on the edge of being able to hold that AOAe number.

The reason the real climb profile is smooth, is because you burn fuel, that is reduce weight continuously rather than in steps.

Far fetched? Problems?


It’s new. 😉

Nicely done, my friend. It’s very informative, and well put together. Will we be seeing a #2? 😜

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(edit note: the following issue has been addressed, see last response below)

Much appreciated, but first I found a bit of a glitch. After reviewing the info, what I wrote appears to support max endurance as opposed to max range. The max range AOA is also a fixed number, and shouldn’t be a whole lot different, but getting at it in an intuitive way, is a bit trickier. A rule of thumb adjustment may be in the works…need to look at the math a bit more, ouch!..

Very informative article!

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(edit note: this has now been addressed - see further below, thanks)

Thanks! I’m trying to work on a refinement or two, with the idea that AOA is a primary instrument of flight. The idea goes back to the Wright Brother’s written records, and in modern aviation appears to span multiple issues of flight. It’s perhaps the most overlooked “how am I flying” instrument reading.

I’ll briefly refine the idea of target AOA for performing various phases of flight, such as the goal of best step climb as described above.

AOA is important throughout the various phases of flight. Though you don’t need to always watch it with obsessive precision in mind, you would always be somewhat aware of AOA through pitch (nose above the horizon) as a first state of awareness.

During transitions in speed and attitude it pays to watch AOA with increased attention, in particular during the transition to a stabilized approach.

There are likely 4 AOA targeting concepts that flesh out the range of issues you are likely to encounter in reading about AOA:

1)best duration AOA (longest time on a pound of fuel)
2)best range AOA (MSR - best distance on a pound of fuel)
3)long range cruise AOA (LCR - typically 99% of MSR)
4)a reasonable safe range of AOA to avoid stall (to maintain flight)

The first gives you the lowest fuel loss from drag.

The second pays some fuel for a bit more drag, in exchange for more speed that maximises the distance (rather than time) from a pound of fuel.

The third stretches beyond the optimum distance from fuel (second), to trade 1% loss of that range for an average of 10% more speed. This gets you to your destination faster, within a reasoned fuel penalty trade-off.

Consider the fourth point above to apply, in particular, for attitude and speed transitions.

Also watch AOA as your guide of when to change flap settings.

Which angle starts to cause you problems in your aircraft type (such as stall in a turn to approach)? Perhaps 6 degrees. Or more or less?

For whatever aircraft type you’re flying, you can experiment to find which of these limited AOA readings gives you the best targeting outcome.

Suggestion: Start with 4 degrees to answer all of the first three concepts listed above.

As your AOA starts squeezing below 4, see that it means you are increasingly trading economy for distance, then progressing to shortest time to destination (with some drag induced fuel penalty as the angle decreases).

Angle of Attack means: how am I flying aerodynamically?

For a different aircraft type, see if your starting target is best 4 degrees, or should be changed to 3 or 5 degrees. Then you can use that target forever for that aircraft.

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Hmm, this is cool!

I will 100% try this.

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Ideas on reading AOA.

Not so long ago in IF, AOA started showing up as an instrument displayed in cockpit view for some aircraft types (how many?). Only in the latest version has AOA appeared as an option to display at the bottom of HUD view.

But AOA has been around in IF as long as the FPV (little circle in HUD view) has been around. The FPV graphically gives you that information, which is invaluable. Being graphical, it’s more intuitive than a numeric readout, but at the expense of precision. I love that I can now verify the exact number that my eyeballs believe from the FPV by cross referencing the exact AOA angle at the bottom of the HUD. It’s a useful brain calibration exercise.

But it’s also very cool to be able to sometimes watch your flight from an outside drone view, while being able to fine tune with reference to the AOA number! (obviously you can’t see the FPV in this view)

Reading AOA from the FPV

FPV of course shows you the direction your aircraft is traveling. You read the AOA angle by how much the FPV circle is vertically separated from the HUD’s nose mark. It’s an eyeball estimation using the 5 and 10 degree pitch mark as your measuring stick. You’ll notice the numeric AOA number, always agrees with the FPV .

According to need for your AOA information, sometimes you’ll look at one of the two in preference to the other; at other times you compare them with each other.

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I think that if this was cleaned up a bit, it could be changed to a #ground-school:community-tutorials! Great job.

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Thank you! I certainly see your point. Part of the question I have is when am I up enough on the learning curve to do the cleaning, and also whether I want to fold another issue into it or keep them separate…Your comment much appreciated!

But I don’t believe I can post in the community-tutorials as my trust level is basic…

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